U.S. Pat. No. 4,982,716 describes a fuel injector for injecting an air-fuel mixture which, at the downstream end of a nozzle body, has an adapter into which air can be introduced. The air is supplied via two supply ducts or supply orifices, which run obliquely to the longitudinal valve axis and open through into an inner spray-discharge region of the adapter to allow the air to collide with the fuel either upstream or downstream from a centrally arranged collision surface. The collision surface partitions the fuel into two spray-discharge orifices. Over their length, the air-supply ducts have a constant diameter and a circular cross-section. To assure a precise metering-in of the air, the metering cross-section must be fabricated to very exact dimensions. Since the entire adapter has to be manipulated when the supply ducts are inserted, this machining step is relatively costly. Moreover, once the supply ducts have been inserted, one can no longer vary their size.
The above applies to fuel injectors as well, as disclosed, for example, in German Patent No. 41 03 918 and U.S. Pat. No. 5,035,358. Here, as well, air supply ducts, which always exhibit a constant diameter and circular cross-section, are provided in an adapter housing body on the valve. The supply ducts are, again, inserted directly in the housing body, so that the entire housing body has to be handled in order to machine them.
Therefore, in known injectors where air is supplied in an ancillary housing body, the two functions of supplying or metering air and of mounting on the injector must be jointly approached, so that it is hardly possible to optimally realize both functions because of the integration.
Therefore, in known fuel injectors, air is supplied in a housing body through air-supply ducts which are directed toward the fuel in a central orifice. These housing bodies are formed in one piece, making it impossible to variably meter in air and aggravating the insertion of the air-supply ducts.